For 6 varieties of dahlia, heavy root storage was correlated with a short day, and a fibrous root system with a long day. Flowering was independent of storage root formation, although certain varieties, (Jersey''s Beauty and Mrs. I. de ver Warner) flowered and formed storage roots concurrently on a short day. Certain varieties (Arthur and Summer Red) flowered independently of day length, while others (Jersey''s Beauty and Warner) flowered only on a short day. Cuttings taken during late Sept. and Oct. developed various types of storage organs along the stem without forming either typical storage roots or fibrous roots. Nitrates accumulated in the leaves and stems of short day plants, but were absent or present in only small amounts in long day plants. The pH of stems or leaves of long and short day plants varied only slightly from 5.4.